Other Utilities

Note

This documentation page is aimed at developers who want to customize, change or extend the code of OpenWISP Utils in order to modify its behavior (e.g.: for personal or commercial purposes or to fix a bug, implement a new feature or contribute to the project in general).

If you aren't a developer and you are looking for information on how to use OpenWISP, please refer to:

Model Utilities

`openwisp_utils.base.UUIDModel`

Model class which provides a UUID4 primary key.

`openwisp_utils.base.TimeStampedEditableModel`

Model class inheriting UUIDModel which provides two additional fields:

created
modified

Which use respectively AutoCreatedField, AutoLastModifiedField from model_utils.fields (self-updating fields providing the creation date-time and the last modified date-time).

REST API Utilities

`openwisp_utils.api.serializers.ValidatedModelSerializer`

A model serializer which calls the model instance full_clean().

`openwisp_utils.api.apps.ApiAppConfig`

If you're creating an OpenWISP module which provides a REST API built with Django REST Framework, chances is that you may need to define some default settings to control its throttling or other aspects.

Here's how to easily do it:

from django.conf import settings
from django.utils.translation import ugettext_lazy as _
from openwisp_utils.api.apps import ApiAppConfig


class MyModuleConfig(ApiAppConfig):
    name = "my_openwisp_module"
    label = "my_module"
    verbose_name = _("My OpenWISP Module")

    # assumes API is enabled by default
    API_ENABLED = getattr(
        settings, "MY_OPENWISP_MODULE_API_ENABLED", True
    )
    # set throttling rates for your module here
    REST_FRAMEWORK_SETTINGS = {
        "DEFAULT_THROTTLE_RATES": {"my_module": "400/hour"},
    }

Every openwisp module which has an API should use this class to configure its own default settings, which will be merged with the settings of the other modules.

Storage Utilities

`openwisp_utils.storage.CompressStaticFilesStorage`

A static storage backend for compression inheriting from django-compress-staticfiles's CompressStaticFilesStorage class.

Adds support for excluding file types using OPENWISP_STATICFILES_VERSIONED_EXCLUDE setting.

To use point STATICFILES_STORAGE to openwisp_utils.storage.CompressStaticFilesStorage in settings.py.

STATICFILES_STORAGE = "openwisp_utils.storage.CompressStaticFilesStorage"

Other Utilities

`openwisp_utils.utils.get_random_key`

Generates an random string of 32 characters.

`openwisp_utils.utils.deep_merge_dicts`

Returns a new dict which is the result of the merge of the two dictionaries, all elements are deep-copied to avoid modifying the original data structures.

Usage:

from openwisp_utils.utils import deep_merge_dicts

mergd_dict = deep_merge_dicts(dict1, dict2)

`openwisp_utils.utils.default_or_test`

If the program is being executed during automated tests the value supplied in the test argument will be returned, otherwise the one supplied in the value argument is returned.

from openwisp_utils.utils import default_or_test

THROTTLE_RATE = getattr(
    settings,
    "THROTTLE_RATE",
    default_or_test(value="20/day", test=None),
)

`openwisp_utils.utils.print_color`

default colors: ['white_bold', 'green_bold', 'yellow_bold', 'red_bold']

If you want to print a string in Red Bold, you can do it as below.

from openwisp_utils.utils import print_color

print_color("This is the printed in Red Bold", color_name="red_bold")

You may also provide the end argument similar to built-in print method.

`openwisp_utils.utils.SorrtedOrderedDict`

Extends collections.SortedDict and implements logic to sort inserted items based on key value. Sorting is done at insert operation which incurs memory space overhead.

`openwisp_utils.tasks.OpenwispCeleryTask`

A custom celery task class that sets hard and soft time limits of celery tasks using OPENWISP_CELERY_HARD_TIME_LIMIT and OPENWISP_CELERY_SOFT_TIME_LIMIT settings respectively.

Usage:

from celery import shared_task

from openwisp_utils.tasks import OpenwispCeleryTask


@shared_task(base=OpenwispCeleryTask)
def your_celery_task():
    pass

Note: This task class should be used for regular background tasks but not for complex background tasks which can take a long time to execute (e.g.: firmware upgrades, network operations with retry mechanisms).

`openwisp_utils.utils.retryable_request`

A utility function for making HTTP requests with built-in retry logic. This function is useful for handling transient errors encountered during HTTP requests by automatically retrying failed requests with exponential backoff. It provides flexibility in configuring various retry parameters to suit different use cases.

Usage:

from openwisp_utils.utils import retryable_request

response = retryable_request(
    method="GET",
    url="https://openwisp.org",
    timeout=(4, 8),
    max_retries=3,
    backoff_factor=1,
    backoff_jitter=0.0,
    status_forcelist=(429, 500, 502, 503, 504),
    allowed_methods=(
        "HEAD",
        "GET",
        "PUT",
        "DELETE",
        "OPTIONS",
        "TRACE",
        "POST",
    ),
    retry_kwargs=None,
    headers={"Authorization": "Bearer token"},
)

Paramters:

method (str): The HTTP method to be used for the request in lower case (e.g., 'get', 'post', etc.).
timeout (tuple): A tuple containing two elements: connection timeout and read timeout in seconds (default: (4, 8)).
max_retries (int): The maximum number of retry attempts in case of request failure (default: 3).
backoff_factor (float): A factor by which the retry delay increases after each retry (default: 1).
backoff_jitter (float): A jitter to apply to the backoff factor to prevent retry storms (default: 0.0).
status_forcelist (tuple): A tuple of HTTP status codes for which retries should be attempted (default: (429, 500, 502, 503, 504)).
allowed_methods (tuple): A tuple of HTTP methods that are allowed for the request (default: ('HEAD', 'GET', 'PUT', 'DELETE', 'OPTIONS', 'TRACE', 'POST')).
retry_kwargs (dict): Additional keyword arguments to be passed to the retry mechanism (default: None).
**kwargs: Additional keyword arguments to be passed to the underlying request method (e.g. 'headers', etc.).

This method will raise a requests.exceptions.RetryError if the request remains unsuccessful even after all retry attempts have been exhausted. This exception indicates that the operation could not be completed successfully despite the retry mechanism.

Test Utilities

OpenWrt Agents